Ever wondered why your muscles are so sore after exercise

A common misunderstanding about muscle soreness is that it is due to lactic acid build-up in the muscles. It's actually not!
Share this article

As many of us hit the gym or go for a run to recover from the silly season, you might notice a bit of extra muscle soreness.

This is especially true if it has been a while between workouts.

A common misunderstanding is that such soreness is due to lactic acid build-up in the muscles.

Research, however, shows lactic acid has nothing to do with it. The truth is far more interesting, but also a bit more complex.

It’s not lactic acid

We’ve known for decades that lactic acid has nothing to do with muscle soreness after exercise.

In fact, as one of us (Robert Andrew Robergs) has long argued, cells produce lactate, not lactic acid. This process actually opposes not causes the build-up of acid in the muscles and bloodstream.

Unfortunately, historical inertia means people still use the term “lactic acid” in relation to exercise.

Lactate doesn’t cause major problems for the muscles you use when you exercise. You’d probably be worse off without it due to other benefits to your working muscles.

Lactate isn’t the reason you’re sore a few days after upping your weights or exercising after a long break.

So, if it’s not lactic acid and it’s not lactate, what is causing all that muscle soreness?

A woman clasps her lug in pain.
Regular training will gradually build the muscle adaptations necessary to prevent delayed onset muscle soreness. Shutterstock

Muscle pain during and after exercise

According to The Conversation when you exercise, a lot of chemical reactions occur in your muscle cells. All these chemical reactions accumulate products and by-products which cause water to enter into the cells.

That causes the pressure inside and between muscle cells to increase.

This pressure, combined with the movement of molecules from the muscle cells can stimulate nerve endings and cause discomfort during exercise.

The pain and discomfort you sometimes feel hours to days after an unfamiliar type or amount of exercise has a different list of causes.

If you exercise beyond your usual level or routine, you can cause microscopic damage to your muscles and their connections to tendons.

Such damage causes the release of ions and other molecules from the muscles, causing localised swelling and stimulation of nerve endings.

This is sometimes known as “delayed onset muscle soreness” or DOMS.

While the damage occurs during the exercise, the resulting response to the injury builds over the next one to two days (longer if the damage is severe). This can sometimes cause pain and difficulty with normal movement.

A woman does lunges in the gym.
Being less wrecked by exercise makes it more enjoyable. Shutterstock

The upshot

Research is clear; the discomfort from delayed onset muscle soreness has nothing to do with lactate or lactic acid.

The good news, according to The Conversation, is that your muscles adapt rapidly to the activity that would initially cause delayed onset muscle soreness.

So, assuming you don’t wait too long (more than roughly two weeks) before being active again, the next time you do the same activity there will be much less damage and discomfort.

If you have an exercise goal (such as doing a particular hike or completing a half-marathon), ensure it is realistic and that you can work up to it by training over several months.

Such training will gradually build the muscle adaptations necessary to prevent delayed onset muscle soreness. And being less wrecked by exercise makes it more enjoyable and more easy to stick to a routine or habit.

Finally, remove “lactic acid” from your exercise vocabulary. Its supposed role in muscle soreness is a myth that’s hung around far too long already.

Try these Simple 5 minute warm-up and cool-down exercises for mums of all fitness levels.

7 tips for muscle recovery

There are things you can do to alleviate the soreness as well. Here are our top tips:
10 ways to stretch

1. Stretch it out

To avoid too much muscle soreness post-exercise, the best thing is to stretch more before and after exercises.

2. Warm up and cool down

Before and after your workout, it’s imperative to include a good warm up and cool down.

3. Work on strength and flexibility

Try to incorporate exercises with strength and flexibility components such as Pilates or full body functional exercises that are in The Healthy Mummy HIIT APP.

4. Have an Ice Bath

Ice baths may help reduce muscle pain and soreness, and limit the inflammatory response after exercise.

5. Have an Epsom salt bath

A good hot soak in the bathtub is also a great way to recover post workout and avoid muscle soreness. Having an Epsom salt bath is also more powerful than taking magnesium supplements orally as the skin absorbs the magnesium better in a bath.

6. Try creatine supplements

You can also take supplements to avoid too much muscle soreness. Creatine is an amino acid which helps the body send energy to your muscle cells and your body repairs quicker as a result.

7. Use foam rollers

Foam rollers are a great way to deal with stubborn muscle soreness and are cheaper than a massage!

Drop a Dress Size

Ready to Drop a Dress Size in 28 Days?

Never Go Hungry

Our program offers NO 1200 calorie restrictions

Workout at Home

Follow guided training videos with expert fitness instructors (no equipment needed!)

Feel Supported 24/7

In our private support groups with other mums just like you!

Eat Delicious and Healthy Food

With family-friendly, weekly meal plans & over 6,000 easy recipes developed by nutritionists


No lock-in contracts, cancel anytime.

Share this article

Be part of our friendly and supportive community

Want FREE delicious recipes, fitness tips and great specials?